Fort du Bois d'Oye
Belfort, France
Fort Bois d'Oye, also known as Fort Eblé, is located in the commune of Bermont. It was built between 1883 and 1886. It is part of the second ring of fortifications around the city of Belfort in northeastern France. This second ring of forts was built as part of the Séré de Rivières system and incorporated improvements to deal with the improvement in efficacy of artillery in the late 19th century.
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).